Superjunction Transistor Doping Profiles for Avalanche Robustness
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Solution Overview
Problem
Superjunction transistor devices face challenges in achieving low on-resistance and high avalanche robustness while maintaining voltage blocking capability, as they are prone to overheating and destruction due to prolonged avalanche current.
Innovation Solution
The design includes a transistor device with specific doping concentrations and profiles in the drift and compensation regions, where the first doping concentration of the drift region is higher than a certain threshold and the second doping concentration of the compensation region is also higher than another threshold, optimized to minimize on-resistance and enhance avalanche robustness, with a control structure connecting the drift and compensation cells to the source node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the doping concentration of the drift region is increased to reduce on-resistance, then the on-resistance decreases, but the breakdown voltage capability deteriorates
Solution Approach 1:
The drift region is segmented into multiple cells, each with its own compensation region, forming a modular structure. This segmentation allows each cell to be independently optimized for both low resistance and high breakdown voltage, while the collective array achieves overall low on-resistance without sacrificing voltage blocking capability.
Solution Approach 2:
Different regions within the drift region are assigned different doping concentrations. The drift region has a first doping concentration optimized for low resistance, while the compensation region has a second doping concentration optimized for voltage blocking. This local differentiation allows each region to perform its specific function optimally without compromising the other.
2Reliability
If the transistor device is designed to withstand avalanche current for extended periods, then the avalanche robustness improves, but the device temperature increases leading to thermal destruction
Solution Approach 1:
The compensation region is designed with specific doping characteristics beforehand to cushion and distribute the avalanche current stress. This pre-designed compensation structure prevents localized overheating by spreading the power dissipation across multiple cells and regions, allowing the device to withstand avalanche events without thermal destruction.
Solution Approach 2:
The avalanche current is distributed across multiple segmented cells rather than concentrated in a single region. Each cell handles a portion of the total avalanche power dissipation, preventing any single location from reaching destructive temperature levels even during extended avalanche events.
3Loss of energy
If the doping concentration in the drift region is increased to reduce on-resistance, then the conduction loss decreases, but the avalanche current承受能力 deteriorates
Solution Approach 1:
The drift region and compensation region are assigned different local doping qualities. The drift region uses a first doping concentration optimized for low conduction loss, while the compensation region uses a second doping concentration optimized for avalanche current handling. This local quality differentiation allows the device to achieve low conduction loss without sacrificing avalanche robustness.
Solution Approach 2:
The device is segmented into drift region cells and compensation region cells that work together. The drift region provides low-resistance conduction paths during normal operation, while the compensation region provides avalanche protection, allowing the device to achieve both low conduction loss and high avalanche current承受能力 through the collaborative function of segmented regions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design results in a transistor device with a remarkably low specific on-resistance and high avalanche robustness, capable of withstanding avalanche states without damage and efficiently switching between on and off states, suitable for use in power converter circuits.
Implementation Method 1
When the voltage reaches the breakdown voltage an avalanche breakdown occurs that causes an avalanche current to flow. The avalanche breakdown is associated with an acceleration of charge carriers in the drift region such that they create electron-hole pairs by impact ionization.
Implementation Method 2
The avalanche breakdown is associated with an acceleration of charge carriers in the drift region such that they create electron-hole pairs by impact ionization.
Data Source
AI summary
A power converter circuit includes an inductor and rectifier circuit having an inductor connected in series with an electronic switch, and a rectifier circuit, and a controller for generating a drive signal for driving the electronic switch. The electronic switch has drain, source and gate nodes, drift and compensation cells each including a drift region of a first doping type and a compensation region of a second doping type, and a control structure connected between the drift region of each of the drift and compensation cells and the source node. Each drift region is coupled to the drain node and each compensation region cells is coupled to the source node. A first type doping concentration N1 of the drift region is higher than a first doping level L1, and a second type doping concentration N2 of the compensation region is higher than a second doping level L2.